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Scope of the PAR The document recommends best engineering practices for the installation and deployment of IEEE 802.22 systems to help assure that such systems are correctly installed and deployed.

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Purpose To provide detailed technical guidance to installers, deployers, and operators of IEEE 802.22 compliant systems to help assure that such systems are correctly installed and deployed.

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Need for a Recommended Practice Correct installation and deployment of IEEE 802.22 compliant systems are important to assure that those systems will maximally achieve their design goals in terms of system performance, reliability, and non- interference to incumbent licensed systems with which they will share the TV broadcast bands.

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How it all started! The FCC released a Notice of Proposed Rulemaking, May 25, 2004, proposing to allow unlicensed radio transmitters to operate in the broadcast television spectrum at locations where that spectrum is not being used.

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Fixed/Access Transmitter power limit: 1 W Transmitter antenna gain limit: 6 dBi An incumbent database is required. Geo-location technique is required using either a GPS or professional installation. Transmission of a unique identifier is necessary. Spectrum sensing approach is postulated.

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Cognitive Radio Allows spectrum sharing on a negotiated or opportunistic basis. Adapts a radios use of spectrum to the real- time conditions of its operating environment. Offers the potential for more flexible, efficient, and comprehensive use of available spectrum. Reduces the risk of harmful interference.

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Cognitive Radio Techniques (as per the NPRM) 1. Database/Geo-Location: Determine whether the unlicensed device is outside the protected contour of a licensed station using a database with a geo- location device. 2. Control Signal: Receive a control signal from an established incumbent service indicating which channels are available or are occupied in the area. 3. Sensing: Sense the RF environment to a certain threshold to detect whether a TV channel is in use.

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1- Problems with the Proposed Database/Geo-Location Technique (as per the NPRM) Databases can have mistakes and can be inaccurate. Databases are not updated instantaneously with real-time changes in the RF environment. GPS does not operate well indoors (CPE antenna has to be outdoors anyway). Solution: Databases/geolocation techniques could be used for first assessment of channel availability but need to be supplemented by sensing.

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2- Problems with the Proposed Control Signal Technique (as per the NPRM) Control signals indicating available channels from different sources may overlap and cause confusion. Control signals indicating occupied channels from different sources may overlap and cause confusion. No incentives for incumbent services to provide control signals for unlicensed operation. Solution: control signal provided by the base station

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3- Problems with Sensing (as per the NPRM) The detectable RF environment changes dramatically with minor changes in location of the sensing device due to multi-path, fading, or shadowing. The hidden node problem occurs when a sensing device is being shadowed by either a man-made structure or terrain and cannot accurately detect what TV channels are occupied. Solution: collaborative sensing from a number of CPEs and data fusion/centralized control at the base station, augmented by geolocation/database.

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Need for Recommended Practice Recommended Practice is needed to help operators make best use of the spectrum while protecting incumbents Installation and deployment requirements to protect incumbents need to be well understood Typical WRAN deployment and installation need to be explained to new potential operators Capabilities and limitations of the 802.22 standard need to be known Impact of departure from typical operation needs to be understood

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Best practices for base station siting and installation: Site selection and frequency selection based on local TV channel usage Use of computer based coverage prediction tools and databases to identify potential coverage area and potentially affected incumbents Transmit antenna and power constraints for given location Co-existence with neighbour WRAN operators

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Best practices for Base Station operation and performance verification: Continuous monitoring of the interference environment Normal sensing reporting Special sensing request to CPEs and reporting Data fusion and automatic and/or manual frequency channel control Interface with the incumbents for interference resolution Smooth increase of service provision by using multiple channels Load balancing Fall-back scheme in case of interference and insufficient channels Monitoring of key operational and performance parameters

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Best practices for CPE installation and control: Verification of physical location (at registration, GPS, relative position among CPEs) Verification of the installation (10 m high antenna, right azimuth, fixed installation: remote, visual) Instruction to new subscribers (installation and antenna alignment, problem identification, network access) Guidance on serving subscribers near the edge of the coverage versus system loading and interference potential

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Best practices for interference avoidance: Optimizing collaborative sensing based on a number of well positioned CPEs relative to an incumbent operation Techniques for improved coexistence among WRAN operators in the same area

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Best practices for Part 74 device protection How to maximize the sensing capability of BS and CPEs for wireless microphones and the limitations Use of enhanced detection schemes (TG1) Means for the operator to avoid interference Channel switch in the local vicinity based on location information

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Conclusions 802.22 sees a compelling need to develop such a Recommended Practice The PAR was everwhelmingly approved by the 802.22 WG members Licensed incumbents wholeheartedly support the development of this Recommended Practice 802.22 wants to proceed and will be seeking EC approval to submit the PAR to NesCom